However, the conventional FFD methods can not solve the existing problems in current system because of either inconvenient control tools or large time and space costs.

• 但是，已有的这类方法或者控制手段不够灵活，或者时间和空间开销较大，且各类变形方法都有其自身的适用场合，不适于解决现有工作中遇到的问题。